In my previous U.S. Pat. No. 3,173,979 I described a device for the same purpose as this invention, however, that device is bulky and complicated, and is a fixed machine, located outside of a shop. The present invention is a machine greatly reduced in size and simple in structure, having novel means for vertical adjustment and having a pivotal base, providing a machine mountable on a skid and thus easily transported, simple to operate and relative to the former device, less costly to manufacture.